Calculation Method of Flange Installation

The flange is a kind of detachable connection that can maintain a sealing effect within a certain pressure range.

The working condition of the flange is composed of a pair of flanges, several bolts, nuts, a gasket and a washer. Under the tensioning action of the bolt, the flange compresses the gasket between the compression surfaces, thereby maintaining a sealed connection under a certain pressure.

The calculation method of flange installation engineering quantity is as follows:

• The installation of various flanges on low, medium and high-pressure pipelines, pipe fittings, flanges and valves should be calculated according to different pressures, materials, specifications and types in units of “pairs” (that is, a pair of flanges). The pressure level shall be rated according to the design drawings.
• For stainless steel and non-ferrous metal welding ring movable flange installation, the corresponding quota of flanging movable flange installation can be performed, but the short flanged pipe in the quota should be replaced with a welding ring, and its value should be calculated separately.
• The gaskets installed on the low and medium-pressure flanges are considered asbestos rubber sheets and can be adjusted if the design has special requirements.
• For medium-pressure threaded flange installation, the installation cost shall be calculated by multiplying the low-pressure threaded flange item by 1.2.
• The installation of high-pressure carbon steel threaded flanges includes the work of applying molybdenum disulfide to the bolts.
• The high-pressure butt welding flange includes the oil coating on the sealing surface but does not include the bolt coating molybdenum disulfide, graphite oil or graphite powder. The hardness inspection shall be calculated separately according to the design requirements.
• For pipes connected with flanges, the engineering quantities of pipes and flanges are calculated separately, and corresponding quotas are implemented. For example, the length of the pipe section is 100m and it is connected with 5 pairs of flanges. The engineering quantity is 100m of pipe connection and 5 pairs of flanges.
• Flange installation does not include the contents of cold and hot fastening during system commissioning and operation after installation, which will be calculated separately when it occurs. The blind plate matched with the flange only calculates the main material cost, and the installation cost has been included in the single-piece flange installation.

• The following sub-items should be multiplied by the coefficient to calculate:

  (1) The throttling device installed on the pipeline shall be calculated by multiplying the corresponding quota of flange installation by a coefficient of 0.8.
  (2) The welding blind plate (head) is calculated by multiplying the corresponding items of the pipe fittings by the coefficient 0.6.
  (3) The medium-pressure flat-welding flange is calculated by multiplying the low-pressure flat-welding flange item by a factor of 1.2.
  (4) For the flange installation of the full heating sleeve, the corresponding quota is multiplied by the coefficient 2.0 according to the diameter of the inner sleeve flange.
  (5) When the flange installation takes “pieces” as the unit of measurement, the calculation of the flange installation quota multiplied by the coefficient 0.61 is performed, and the number of bolts remains unchanged.
• Please send your inquiry to us for your projects. We are sure to supply you with satisfactory products and services.
•